The present invention relates to a construction of a microwave oven and, more particularly, to a cooling system and a magnetic shield system for a microwave oven or a combined electric heating oven and microwave oven.
Recently, a semiconductor chip has been incorporated within a heating appliance such as a microwave oven. The semiconductor chip is adapted to control the heating appliance as-shown in T. KAWABATA et al, Ser. No. 792,222 "MICROWAVE OVEN WITH A PROGRAMMABLE DIGITAL CONTROL CIRCUIT" filed on Apr. 29, 1977, U.S. Pat. No. 4, 255,639 assigned to the present assignee. The semiconductor chip has a tendency to be easily damaged by heat evolved within the housing of the heating appliance. The heat problem imparted to the semiconductor chip to results in a mismanagement of the heating appliance.
Furthermore, the microwave oven has evolved to the present stage wherein a magnetic card is used to provide input cooking information according to which the microwave oven is energized. Such a microwave oven was disclosed in a copending U.S. patent application Ser. No. 974,037, entitled "MAGNETIC CARD CONTROL MICROWAVE OVEN" filed on Dec. 27, 1978 by K. DOI et al, assigned to the present assignee.
In such a magnetic card-controlled microwave oven, it is required that a plurality of circuit elements inclusive of the semiconductor chip be protected magnetically from a high-voltage transformer disposed within the magnetic card-controlled microwave oven.